This invention relates generally to fitting or accessory installation in an electrical junction box, and more particularly pertains to means for obtaining a secure stabilized placement of the fitting in the junction box.
In new building and home construction, it is common practice, once structural framing is completed, for the electrician to place electrical outlet and switch utility boxes pursuant to plan and then run electrical cables to the boxes prior to installation of lathe and plaster or plasterboard or other interior wall surface material. Ideally, when the electrician returns to complete his work by installation of the socket fittings and switches, etc, he needs only to complete the connection of the exposed cable ends, protruding from each utility box, to the fitting, then install the fitting in place within the utility box, prior to affixing the appropriate appearance cover plate. Such work can be quickly and uniformly accomplished if the forward edge of the utility box is in vertical alignment with the wall surface, however, there is often misalignment due to a twisted or bowed condition of the stud to which the utility box is mounted. Also, even when the degree of misalignment is not excessive, there is often the additional problem caused by the excessived size of the wall surface opening which surrounds the utility box. This problem is prevalent where plasterboard installer use a router to rough out an opening in a plasterboard wall surface to generally coincide with the utility box position.
In any of the situtations heretofore described, the electrician must fasten an accessory or fitting, such as a dual socket or switch, in the utility box, leaving the mounting screws in an unseated position whereby the fitting "floats" on the box. Stabilization of the fitting then may depend upon the oppositely extending metal ears of the fitting abutting against the wall surface. Where the opening about the box is too large whereby the ears will not reach the wall surface, stabilization becomes a matter of pulling the fitting into proper aligned position by means of the attachment of the appearance cover plate, and the fitting nevertheless often remains loose relative to the utility box.
Stabilization by pressure of the peripheral undersurface of the cover plate against the wall surface is often only temporary since the strain on the cover plate will often distort or fracture the plate either as an incidence of its installation or at a later time. One corrective measure has been to provide cover plates formed from high-strength and comparatively expensive plastic such as polycarbonate which is comparatively resistant to strain fracture. Limited shifting of the fitting in a vertical plane may still occur even where the integrity of the cover plate is assured by the strength of its composition. In any event, if a fitting is able to shift relative to the utility box, the electric cable or wire end connections to the fitting are flexed each time the fitting is caused to move relative to the box, thus creating a fire hazard if the wire breaks or works loose and results in current arcing. Where the fitting is a dual socket, the insertion and withdrawal of plugs moves the fitting against its wire connections, running the risk of eventual wire severance. Where the fitting is a switch assembly with a toggle or dimmer dial, an undesirable shifting of the fitting can occur each time manual force is applied to manipulate the switch.
The foregoing problems have been recognized and previously addressed by various means in the prior art. For the situation where the utility box is disposed backwardly from the wall surface and the opening in the wall surface about the utility box is excessive, an oversize appearance cover plate has been provided for use in combination with a back-up flat sheet metal shim plate. This approach creates a stabilizing tension between the fitting and the wall surface but does not entirely solve the problem of the floating fitting and its tendency to shift relative to the utility box due to the unseated mounting screws.
In addition to the commercially introduced devices which have been made available over the years to achieve stabilization of an electrical fitting with a utility box, various on-site means are often employed by innovative electricians to compensate for situations where utility boxes are mounted in misaligned orientation and to achieve firm attachment of electrical fittings to such boxes. It is not uncommon to employ multiple washers on the mounting screw between the fitting ear and the utility box or to jam pieces of cardboard or plastic onto the screw shank in order to fill the void between the fitting ear and the box and thus shim the connection. Plastic tabs have, in fact, been made commercially available for this purpose. Such tabs, whether used singly or in plural stacks, have the disadvantage of permanent deformation which generally results in later loosening of the connection.
One early attempt to solve the aforedescribed problems is found in U.S. Pat. No. 2,291,107 wherein socket supporting elements, in the form of a pair of transversely extending shim plates, are provided to be carried on the utility box mounting screw with opposite ends extending laterally to overlie the wall surface beneath the appearance cover plate. The structure of this invention depends on stabilizing the fitting to the wall surface but does not address stabilization of the fitting directly to its junction box.